Printing-press.



B. D. STEVENS. PRINTING PRESS.

APPLICATION FILED SEPT. 1 1. 19-] I.

11 %,$a Patented July 13, 1915.

ILLINOIS.

PRINTING-PRESS.

Specification of Letters Patent.

Application filed September 11,1911. SerialNdG iiWM. v .i,

To all 107101, it 172 (11 concern Be it known that I, BURT D. STEVENS, a citizen of the United States, residing at Riverside, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Printing-Presses, of which the following is a specification.

My invention relates to printing presses, and refers particularly to the mechanism by which the proper pressure is obtained be-; tween the impression cylinder and the print-- ing form sheet carried by the press-bed or carriage which reciprocates beneath the impression cylinder.

In lithographic printing itis of particular advantage to use sheets of metal instead of lithographic stones on account of the much less cost of the former. In order to prevent the tendency for the sheet of metal to bulge when it is applied to the press-bed, it is of advantage to make the upper surface of said press-bed with a slight convex curve, thereby causing the metal sheet to fit snugly on such upper surface. It has heretofore been customary, as disclosed, for example, in Patent No. 932,100, granted to B. F. Berry, to operate the press-bed on a curved track having the same curvature as that of the upper surface of the press-bed so that a uniform pressure will be exerted by the impression cylinder on the surface of the pressbcd as the latter reciprocates back and forth.

It is the object of my invention to do away with the necessity of using a curved track, which is very difficult to construct. I,

employ a straight track on which the pressbed moves, and in order to cause the impression cylinder to maintain a substantially uniform pressure on the press-bed I mount said cylinder in spring-controlled bearings which are movable in a vertical plane. It is of advantage to elevate the impression cylinder on the return stroke of the press-bed,

and in order to accomplish this I employ a cam, or other suitable device, to automatically. accomplish the desired result.

A further object of my invention consists in providing resilient means for exerting pressure between the impression cylinder and the press-bed, irrespective of the shape of the latter and irrespective of whether a straight or a curved trackisused This is a considerable departure and improvement in the art, as heretofore it has been considered necessary to retain the impression cylinder UT srrns Parisian t me,

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in fixed position while it contact i the press-bed, although I- am aware that."

spring' means have, in some cases, been em ployed to move the impression cylinder into.

its inoperative position on thereturn movement of the press-bed. 1 i

These and other advantages of a tron Wlll be more readily understood by ref--v erence to the accompanying drawings, whichshow a preferred embodiment of my im-- provemcnts, and in wlnch-- Figure 1- IS a side elevation of a] I of a prlnting press showing'the press-bed the impression cylinder, and the mechanisinr controlling the same; and Fig.2 is a fragmentary sectional "view taken on the" line; 2-2 of Fig. 1. i

The main frame 5 of the printing presets:

is providedwiththe supportingbrackets,

having the cross-members 7. The bearings y 8 are adapted to reciprocate within thelslots 9 of the brackets 6, and these bearings are, 1, in turn, supported by the rods 10, which extend downwardly to the cross-members ll, which are provided with the downward p110 jections 12,the object of'which will be explained hereafter. Extending between the upper surfaces of the bearings 8 and the brackets 6 are the compression springs 13, which are held in position by the upper ends of the rods 10 and the disks 14, the.

position. of which are regulated by the screws 1.5 so that the tension on the springs 13 may be varied as desired.

The impression cylinder 16 having the shaft 17 is carried by the bearings 8. The press-bed 18- operates on the rollers 19, which, in turn, move on the straight tracks 20. The upper surface of the press-bed is slightly convex, and to it is applied the printing sheet 20, preferably of zinc, and

suitably attached at its ends to the pressinder and occupies a position to the right of the latter, according to the representation shown in Fig. 1, the

lever 22 is in its ele vated position, and, on account of the shape 5 of the cam 21 the bearings 8 are thereby allowed to come into their lowermost positions. The press-bed 18 is now moved to the left in a straight path, and the lefthand end of 10 with the periphery of thBJIIIPIBSSlOIl inder 16. As

the sheet 20 comes in contact cylthe press-bed continues to be moved to the left the upper convex surface of the press-bed 18, or the bearers on th the edges of the the latter to be forced upward tension of the similarly shaped e sides thereof, which engage impression cylinder, causes ly against the springs 13. On account of the very slight degree of curvature of the upper surface of the press-bed 18, the compression of the springs 13 is very slight, and an even tension is thereby obtained rather, on the sheet 20, or,

on the printing sheet of paper which is applied to the latter for the purpose of being printed.

After the press-bed 18 is moved to the left a sufficient distance so that it is freed from the impression cylinder 16, the link 23 is moved downwardly by (which, here shown), the extension suitable mechanism for the sake of simplicity, is not whereby the cam 21 elevates 12, and, thereby, the bearings 8 and the impression cylinder 16. When the press-bed 18 is moved to the right on its return stroke, it is therefore entirely clear of the lmpres It will be sion cylinder 16. readily understood by those skilled in the art that many changes could be made in the detailed construction of the parts which I have described without departing from the spirit or scope of my invention.

What I claim is:

1. Aprinting couple comprising in combination a non-rotarymember having a slightly curved printing surface and arranged to reciprocate in a straight path, a second member adapted to coact with the printing surface on the first member, and means to yieldingly press the two members together in printing relation.

2. A printing couple comprising in combination a non-rotary bed having a slightly convexed printing surface, and arranged to reciprocate in a straight path, an impression cylinder adapted to coact with the printing surface of the bed, and means to yieldingly press the cylinder against the bed in printing relation.

3. A printing couple comprising in combination a non-rotary bed having a slightly convexed printing surface and arranged to reciprocate in a straight path, a rotary impression cylinder mounted in stationary bearings for slight movement toward and from the bed and adapted to co-act with the printing surface thereof, and means to yieldingly press the cylinder toward the bed.

BURT D. STEVENS. 

